(a) Field of the Invention
The present invention relates to an apparatus and method for inserting a null packet. More specifically, the present invention relates to an apparatus and method for inserting a null packet in a digital broadcasting transmission system that periodically inserts a null packet into a video/audio transport stream (TS) and transmits the inserted null packet.
(b) Description of the Related Art
As the use of digital audio has been extended in various applications, such as communications, computers, electric home appliances and so forth, there have been problems related to storage and transmission of a large amount of data.
To solve these problems, the MPEG (Motion Picture Experts Group)-1 standard was formed in 1991 under the supervision of the International Standardization Organization (ISO), and it was expanded for multi-channels to establish the MPEG-2 international standard in November, 1994. MPEG-2 was developed to have broader applications and high-quality pictures, and it is now expected to be used in many fields of industry, including broadcasting, electric home appliances, and communication.
In digital broadcasting transmission systems based on the MPEG-2 algorithm, transmission rates differ from system to system, and the rates are determined from the bit rates of video/audio/data broadcasting signals and null packets.
According to the MPEG-2 international standard, the null packet (i.e., a packet transferred to maintain a constant transmission rate, without effective data) is irregularly inserted solely in consideration of the MPEG-2 decoding buffer model, and it is discarded without use in the decoding step.
More specifically, the null packet has been conventionally used solely for the purpose of maintaining a constant data transmission rate. Namely, in multiplexing video, audio, and data signals, the sum of the bit rates of the signals is compared with the transmission rate, and the null packet is inserted by as much as the deficit.
In the null packet insertion method, the null packet is inconsistently inserted solely in consideration of the MPEG-2 decoding buffer model, as a result of which it is difficult to detect the position of the null packet in the received video/audio transport stream, and worse, it is impossible to use the null packet as an information packet.
Accordingly, there is a demand for an apparatus and method for null packet insertion that regularly inserts a null packet into a video/audio transport stream to be transferred, and uses the inserted null packet to enhance the performance of the digital broadcasting transmission/reception system.